Lubricating oils



Patented Feb. 1,1949

LUBRICATING QILS Bert 11. Lincoln, Ponca City, Okla", and Gordon D.Byrkit, Niagara Falls, N, Y., assignors, by mesne assignments, to TheLubrizol Development Corporation, a corporation of Delaware No Drawing.Application March so, 1945, Serial No. 585,806

12 Claims.

This invention relates broadly to lubricants. More specifically, thisinvention relates to materials which, when added to lubricants, greatlyincrease their resistance to oxidation and formation of corrosiveproducts during use and increase their film strength and often improveother characteristics as well. This application is acontinuation-in-part of our co-pending application Serial No. 461,128,filed October 7, 1942, now Patent No. 2,380,454 granted July 31, 1945,which is in turn a continuation-in-part of our application, Serial No.323,959, filed March 14, 1940, now Patent No. 2,302,703 granted November24, 1942, which is in turn a continuation-inpart of Serial No. 231,362,filed September 23, 1938, now abandoned; and is related to our copendingapplication Serial No. 419,990, filed November 21, 1941, now Patent No.2,418,358, granted April 1, 1947, which is also a continuation-in-partof Serial No. 323,959.

Present-day mechanical devices require lubricating oils of high filmstrength, of high oiliness characteristics, and of low tendency tooxidize during use. It has been found that the presentday hydrocarbonlubricants of the very highest quality are deficient in these veryimportant characteristics. These three properties are of vitalimportance under conditions of thin film lubrication where the lubricanthas been squeezed from between the friction surfaces because of highpressure, slow speeds, and other causes. It is readily seen that theviscosity or the body of the lubricant plays no part in this type oflubrication and that the remaining film of oil must have a very highfilm strength and be of high oiliness value to prevent rupture of thefilm of the lubricant, which would cause seizure. The oil film must tendto keep the coefllcient of friction as low as possible. The oil mustresist oxidation when these thin films are heated in the presence ofoxygen as they are in use.

Mechanical devices are being designed for higher pressure operation, andthe film strength of the best quality straight hydrocarbon lubricant hasbeen found to be too low. It will be obvious that an invention whichprovides a means of improving the film strength of these lubricants isof great importance to the art of lubricant manufacture and to thedesigner and fabricator of mechanical devices.

Substantially all machines operate in Part or at times totally underconditions of boundary or thin film lubrication, under which conditionsthe oiliness or unctuosity of the lubricant is the first and primaryrequisite of emcient operation.

Those skilled in the art of lubricant manufacture or machine manufacturewill readily appreciate the value of an invention that will improve theoiliness of these otherwise high quality lubricants. Furthermore sludgeand acid are especially deleterious under conditions of thin filmlubrication. The sludge is not a lubricant in any sense of the word, andthe soluble acid is particularly corrosive to bearing metals such ascadmium-silver, copper-lead, and the like.

In starting idle mechanical equipment which is lubricated from a sump bypumping or circulating th lubricant, there is always a short period oftime in which the rubbing surfaces must operate under conditions of dryfriction if'ordinary hydrocarbon lubricants are used. With dry friction,the wear on friction surfaces is extreme; and during cold weather whenthe lubricant is sluggish or during periods when the lubricatingsystem'is not functioning properly for one reason or another, rubbingsurfaces may not pnlys'ufler considerable wear but may be'da'm'a'ged tothe point where they must be replaced. The product of our invention hasa veryimportant property of reacting with the metal surfaces,penetrating or adsorbing on the metal surfaces, and leaving a film oflubricant with high oiliness character, which remains on the metalsurface irrespective of the length of time the machine has been idle.

This high oiliness film gives very even and smooth operation, which maybe easily discerned by the experienced operator or lubricating cantswhich are preeminently. satisfactory from the standpoint of oxidation inuse, it is necessary to refine the oil thoroughly and then to add aninhibitor of oxidation. The thorough refining may consist of more andheavier acid treatments "or solvent treating so as to remove aconsiderable,

part of the oil and leave only the most stable portion. Such drasticrefining is necessary in order to obtain stability with respect to'sludge formation but the oil is then subject to easy oxidation to formsoluble acids and other corrosive materials. This can be prevented bythe addition to the refined oil of small amounts of materials whicheither prevent the formation of these corrosive products or by someaction render them inert. Furthermore. such well refined oils aresusceptible to the formation during use of lacquer-like materials whichtend to stick rings. This results in blowby and hence loss of power,failure of lubrication, scratching, scoring, overheating, and eventuallyreplacement of parts. It is practically impossible to refine a lubricantin suchv a manner as to avoid all three of these difficulties, namely,products, and lacquer. It is considerably more advantageous to add thematerials of our invention and avoid these dimculties by this method.

Many of these additive materials are effective when added to poorlyrefined or even wholly unrefined lubricants. The addends may thus besubstituted in whole or in part for the usual refining processes.

In the prior art of applying these principles to the manufacture oflubricants, many diverse types of materials have been suggested to beadded to obtain improvement in various characteristics. It has beenfound that the addition of various organic esters of the oxygen andsulfur acids of phosphorus frequently improves film strength, oxidationresistance, non-corrosiveness, and other characteristics. Nitrogencompounds have been found to inhibit oxidation of oils. Our materialscombine both of these properties.

One object of our invention is to provide improved inhibitors ofoxidation and corrosion for addition to lubricants.

Another object of our invention is to provide film strength improvingaddition agents suitable for use in lubricants and especially incrankcase lubricants.

Other and further objects of our invention will appear in the course ofthe following description.

In general, our invention comprises the addition to lubricating oils ofcertain organic phosphorus compounds characterized by the presence of anatom of phosphorus and an atom of nitrogen which are directly connectedto each other by a double bond. The phosphorus may have a valence of 3or 5. The phosphorus, in addition to being connected to an atom ofnitrogen by means of two chemical bonds, may be directly connected toinorganic atoms such as halogen, oxygen, or sulfur, directly connectedto an organic radical which may be aliphatic, carbooyclic, orheterocyclic, or connected to an organic radical through an inorganiclink which may be oxygen, sulfur, or nitrogen. The pentavalentphosphorus may be connected to various combinations of these radicals.The unsatisfied valence of the nitrogen which is connected to thephosphorus by a double bond may be connected to an organic sludge,soluble corrosive radical which may be aliphatic, carbocyclic, or

heterocyclic in character or it may be connected to an inorganic radicalsuch as nitrogen which may, in turn, be connected to an organic radical,hydrogen, or another inorganic radical such as a halogen.

In accordance with the general statement, this invention is moreparticularly concerned with oil soluble, halogen containing materialscontaining a phosphorus atom and a nitrogen atom linked together with adouble bond and having the general formula: RN:P(Q) 1L where R is anorganic radical containing a benzenoid ring structure; N is tri-valentnitrogen; Q is a monovalent radical which radical upon havingits valencebond satisfied with hydrogen may be vaporized; and which may be eitherhalogen, such as chlorine, or an organic radical, such as ethyl, butyl,amyl, lauryl, etc.; cyclohexyl, methyl cyclohexyl, cyclopropyl, etc.; ornaphthenyl, terpineol, etc.; and n is one or three depending uponwhether the phosphorus is trior penta-valent. Thus, when Q iscyclohexyl, QI-I is cyclohexane, a compound which may be vaporized.

Another preferred type of material possessing an -N:P grouping has thegeneral formula R-N:P(:X) (Q) where R, N and Q are as defined above, andX is an element selected from the class consisting of oxygen andsulphur. Accordingly, when oxygen or sulphur is present, the phosphorusmust have a valence of five. Materials having the structure givenimmediately above are disclosed in our Patent 2,339,710 filed June 1,1942, and issued January 18, 1944.

Compounds having a double bond between a phosphorus atomv and nitrogenatom have outstanding antioxidant properties. We do not know why this istrue, but the characteristic resides in these compounds. We believe thatthe antioxidant activity is a result of the augmented chemicalreactivity at the point of the double bond which is instrumental inreducing to an unusual degree the rate of oxidation and the oxidationtendencies of the fuels and lubricants with which these compounds areblended. With a double bond between the nitrogen and phosphorus atoms,there is a likelihood that these may react with primary valence bonds inan oxidation reaction, thus showing more chemical activity than when allof the valences of the nitrogen and phosphorus atoms are satisfied byprimary valence bonds.

Reference may be made to the United States Patent No. 2,302,703 issuedNovember 24, 1942, on the application of Bert H. Lincoln and Gordon D.Byrkit, Serial No. 323,959, filed March 14, 1940, now Patent No.2,302,703 dated November 24, 1942, and reissued February 29, 1944, No.Re. 22,448, for information relative to the phosphorus-nitrogencompounds having a double valence bond between the nitrogen andphosphorus.

The halogen-bearing organic nitrogen compounds wherein the nitrogen andphosphorus are connected by a double bond are particularly effectiveaddition agents for lubricating oils and fuels. These halogen-bearingcompounds, have the ability to produce the salutary effect of greatlyincreasing the film strength of the lubricant containing the compound asan addition agent of the organic phosphorus-nitrogen compounds describedin Patent No. 2,302,703 but which compound does not contain halogen. Inaddition to the marked increase in the film strength of oil containing ahalogen-bearing addition agent as herein described, as compared to theunblended oil and nonhalogen containing oil, the coeflicient of frictionof an oil into which has been incorporated a small quantity ofhalogen-containing organic phosphorus-nitrogen compound is appreciablyless than the same oil containing a like amount of a halogen-freeorganic phosphorusnitrogen compound. We believe this improvement is dueto the polarity of the compound containing the halogen. Our theory isthat the active halogen atom or atoms chemically activate the organicphosphorus-nitrogen compound in such a manner that the halogen-bearingmolecules are induced to annex themselves on and near the surface of themetallic parts which they contact to form upon such metallic parts aprotective regimented film of multimolecular dimensions which isextraordinarily effective in resisting extreme pressures. This theory isin part substantiated by the fact that these additives enable alubricant to satisfactorily lubricate under nonfluid conditions andunder boundary lubrication conditions. 7

The halogen may be present in the compound in any one or in combinationsof its forms. One or more atoms of bromine, fluorine, iodine, chlorine,or combinations of these elements may be compound may be residualhalogen remaining in the product after preparation or it may beintroduced subsequent to the preparation of the organicphosphorus-nitrogencompound in a separate and distinct halogenationreaction or it may be present in the compound due to both causes.

In connection with this invention, the teaching in our United Statespatent application Serial No. 419,990, filed November 21, 1941, shouldbe noted. There the beneficial eirect of combined sulfur is disclosed.We there disclose in general that organic phosphorus-nitrogen compoundshaving a double bond between the phosphorus and nitrogen atoms may berendered more effective oxidation and corrosion inhibitors by thepresence of sulfur in the organic phosphorus-nitrogen compound.. Thesecompounds containing 1 both halogen and sulfur are particularlyeflective addition agents because the lubricant exhibits great filmstrength, high oiliness, antioxidant, and anticorrosive properties.

Some of these materials which are suitable for use in accordance withour invention are shown in the following outline. All and each of theseare to be considered as examples of our invention when blended in an oilof lubricating viscosity.

A. Sulfophosphazoaryl halides, RN:PSX (R is an aromatic radical and X isa halogen) -1. Sulfophosphazobenzene chloride CaH5N:PSCl 2.Sulfophosphazomethylbenzoate ride, CH30.CO.C6H4N2PSC1 3.Sulfophosphazochloronaphthalene chloride ClCroHsNtPSCl B. Phosphazohalides, R--N:PX (R is an aromatic radical; X is a halogen) 4'.Phosphazobenzene chloride ceHsNzPcl 5. Phosphazoxylene chloride(CH3)zCeI-I3N:PCI

6. Phosphazochlorobenzene chloride C1CsH4NIPC1 7. Phosphazophenylbenzene bromide,

CtHsCsHeN 1 P31 8. Phosphazonitrobenzene bromide,

C. Oxyphosphazo-aryl anilides RNH.PO:NR' (R and R are aromatic radicalsat least one of which contains halogen) v 9.Oxyphosphazobenzochloroanilide ClCeH4NH.P0:NCsHs D.Trichlorophosphanils, RNzPCls 10. Trichlorophosphanil, CoHsN2PCla 11.Trichlorophosphochloranil,

C1CsH4N :PCls

chlo- 6 f i I E. Aryl phosphin-imlnes, RaPiNR' (R' is. aromatic; B maybe aromatic or aliphatic, at least one of the radicals contains halogen)12. Tribenzyl o-chlorophenylphosphinimine, (CsI-IaCHa) 3P NCBHiCl Any ofthese compounds or other members of the classes in the above list ortheir derivatives or any other compound within the limitations set forthin the generic description of this invention may be used and such use iscontemplated as within the scope of this invention.

The compounds of group A of this invention may be made, for example, byreacting an amine which may or may not contain a halogen or an aminederivative which may or may not contain a halogen with (PSCls)thiophosphoryl chloride. The two hydrogen atoms on the amine nitrogenare removed with two chlorine atoms from the PSCla, thus giving thenitrogen phosphorus double bond. The compound will contain residualchlorine because an atom of chlorine, will remain in the radicalrepresenting the thiophosphoryl chloride and may contain halogen becauseof the presence of an amount of chlorine in the amine or aminederivative. The organic radical attached to the amine oramine-derivative may be either open chain or closed chain with onlycarbon or with carbon and other elements, such as nitrogen, sulfur,and'the like. If the organic radical is a closed chain of the aromatictype, various substituents may be placed on the ring. For example,long-chain aliphatic radicals, like petroleum wax, may be substituted.Other organic radicals containing,characteristic groups may also besubstituted; therefore amines of waxylated benzene, naphthalene,cyclohexane, and the like may be reacted with PSCla. Chemicallysaturated and unsaturated aliphatic amines may be employed in making theproduct of our invention. For example, alkyl amineor sulfurized orchlorinated alkyl amine may be employed. Hexyl amine and cyclohexylamine, chlorinated or brominated hexyl amine and cyclohexyl amine, whenreacted with PSCla, give products usable in our invention.

It is to be understood that in practicing our invention, oil-solublehalogen-containing phosphorus-nitrogen compounds of the type describedare to be selected. Some of the compounds within the scope of the broaddefinition of the compounds of use in the practice of this inventionhave only limited solubility'in hydrocarbon oils. It is to beremembered, however, that because of their great efliciency, extremelysmall amounts are often effective. Thus we may use as little as 0.001per cent of some of these compounds, and it will be seen that a fairlyinsoluble material may dissolve to a suflicien't extent to besatisfactory for our purpose. While certain specific examples of thebroad class of halogen-nitrogenphosphorus compounds defined above maynot be extensively oil soluble, only those which are soluble to theextent of at least 0.001% are con- Y the hydrocarbon oil is the use of amutual solvent to bring the addend into solution. Alternatively,peptizing agents may be addedto maintain the organo-phosphorus-nitrogencompound in permanent suspension.

Many of the more diflicultly soluble materials are rendered more solubleby the introduction of alkyl groups, particularly those containing fouror more carbon atoms. The isoamyl, octyl, lauryl, and octadecyl radicalsand radicals from paraflin wax greatly increase the solubility oforganic compounds in oil. One or more of such groups may be introducedas required into the previously described compounds or theirderivatives.

In the selection of a particular compound or compounds to be used as anaddition agent to the hydrocarbon oil, consideration should be given tothe uses for which the blend is designed. Thus, if water is likely to bepresent during use, a phosphorus compound or combination of compounds isselected which is not affected by water. In general, We prefer to usecompounds having boiling points over 250 F. It is sometimes advantageousto combine more than one of these compounds in a blend to obtainparticular properties. We accomplish this by mixing two or more of thesecompounds together and blending the mixture with the hydrocarbon oil orby blending one in the hydrocarbon oil, blending the second into thismixture, and so on until the composition is complete.

The various halogen-phosphorus-nitrogen compounds improve both the filmstrength, oxidation characteristics, and the sludging characteristics ofthe hydrocarbon oil. For example, the sludging tendencies may bedecreased by as little as 0.001 per cent of ourhalogen-phosphorus-nitrogen compounds. The oxidation characteristics oflubricants are very important, and these are markedly improved by ourcompounds. The ability to reduce friction is another feature contributedto lubricants by our halogen-phosphorusnitrogen compounds.

It may be desirable to include in one and the same blend based on ahydrocarbon oil, in addition to the addends here described, otheraddends for specific purposes. Thus, we may add a pour point depressorsuch as a naphthalene-chlor wax condensation product and a viscosityindex improver such as certain resins or polymerized hydrocarbons inaddition to our halogen-containing organo-phosphorus compounds.Furthermore, various metallic compounds may be added to the blendwithout interfering with the action of our ingredients. Indeed, in somecases it is advantageous to combine with our organic halogenbearingphosphorus-nitrogen compounds in a hydrocarbon oil blend such materialsas calcium dichlorostearate, chromium oleate, tin octadecyl phthalate,aluminum stearate, and other metallic soaps.

Our addends are admirably adapted for use in lubricating oils of alltypes including those designed for use in automotive crankcases, Dieseloils, and any other oils of lubricating viscosity such as castor oil,cottonseed oil, lard oil, sperm oil, shale oil. Furthermore, our addendsare advantageously blended in gasoline and other petroleum fuels eitherdirectly or after being blended first in a lubricating oil and thenadded to the fuel. Soap-thickened mineral oils of all types ranging fromthose showing only a slight increase in viscosity over that of themineral oil alone to the semisolid and solid greases containing fiftyper cent or more of soap are amenable to treatment according to ourinvention. In making these greases, the usual soaps such as sodiumstearate, aluminum stearate, calcium soaps of beta fat and the like maybe used. Various other thickening ingredients or materials for otherpurposes may be added. These include yarn, hair, graphite, glycerol,water, lamp black, mica, zinc dust, litharge, and the like.

The following examples of blends of our addition agents are given asillustrations but not as limitations:

In making a lubricating gasoline, we blend 0.5 per cent of the productof Example 1 with gasoline. The product has the composition:

Per cent Gasoline 99.5 Oil .495 Sul-fophosphazobenzene chloride .005

It is to be understood, however, that the hydrocarbon oil in the treatedfuels may be of a viscosity of from about 35 seconds at 100 F. S. S. U.to 350 seconds or more; and the amount of oil blended with thehalogen-phosphorus-nitrogen compound to form the fuel addend may varybetween 0 per cent and 99.5 per cent. In some cases the fuel may beprepared without adding any hydrocarbon oil. The quantity ofhalogen-sulphur-phosphorus-nitrogen compound in the final blended fuelmay vary from 0.0001 to 1.0 per cent or slightly more.

It will be understood that certain features and sub-combinations may beemployed without reference to other species or combinations. This iscontemplated by and is within the scope of our claims. It is furtherobvious that various changes may be made in details within the scope ofour claims without departing from the spirit of our invention. It istherefore to be understood that our invention is not to be limited tothe details described.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described, provided thefeatures stated in any of the following claims or the equivalent of suchbe employed.

We therefore particularly point out and distinctly claim as ourinvention:

1. A lubricant comprising in combination a major proportion of an oil oflubricating viscosity and a minor proportion sufiicient to stabilize theoil against oxidation of an oil-soluble halogen-containing organicphosphorus compound having the general formula R-N:P(Q) where R is anorganic radical containing a benzenoid ring structure; N is trivalentnitrogen; Q is a halogen radical, and n is a small whole number selectedfrom the numerical group consisting of the numbers 1 and three.

2. A lubricant in accordance with wherein Q is chlorine.

3. A lubricant in accordance with wherein Q is a hologen and n is one.

4. A lubricant in accordance with wherein Q is chlorine and n is one.

5. A lubricant in accordance with wherein Q is a halogen and n is three.

6. A lubricant in accordance with claim 1 claim 1 claim 1 claim 1 claim1 wherein Q is chlorine and n is three.

7. A lubricant comprising in combination a major proportion of an oil oflubricating viscosity and a minor proportion from about .001% to about5% by weight of the final lubricant blend of trichlorophosphanil,

8. A lubricant comprising in combination a major proportion of an oil oflubricating viscosity and a minor proportion from about .001% to about5% by weight of the final lubricant blend of phosphazo benzene chloride.

9. A lubricant comprising in combination a major proportion of an oil oflubricating viscosity and a minor proportion from about .001% to about5% by weight of the final lubricant blend of phosphazochlorobenzenechloride.

10. A lubricant comprising in combination a major proportion of an oilof lubricating viscosity and a minor proportion from about .001% toREFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date Re. 22,448 Lincoln et al. Feb.29, 1944 2,109,490 Lipkin Mar. 1, 1938 2,146,584 Lipkin Feb. '7, 19392,279,218 Badertscher Apr. '7, 1942 2,302,703 Lincoln et al. Nov. 24,1942 2,339,710 Lincoln et a1 Jan. 18, 1944

